Terminal plug and block



Jan. 14, 1964 E. E. LEACH TERMINAL PLUG AND BLOCK.

Filed Jur le 23, 1960 FIG. 3

I mum r02 [aw/420 5 154 1 He. /4 p United States Patent "ice 3,117,829 Wi h MAL PLUG AND BLOUK Edward E. Leach, l /hits Bear Lake, Minn assignor to Minnesota Mining and Manufacturing Company, St. Panl, a corporation of Delaware Filed June 23, 195i), tier. No. 38,153 Claims. (Cl. 339-97) This invention relates to wire-connectors, and particular to terminal connectors for attaching to the ends of small insulated wires and for insertion into terminal blocks as in the pin-and-socket interconnecting of con.- municaiton and other electronic equipment and apparatus.

The terminal connector of this invention is directly applied to small insulated copper conductors, either solid or stranded, without preliminary removal of insulation and by simple positive pressure application, to provide a permanent vibration-proof electrically conductive contact. The connector may then be inserted into the terminal block for either permanent or temporary connection to one or more similar components, as in the wiring of communication apparatus, radio or television receiving sets, or other electronic apparatus.

In the drawing:

FEGURES 1-3 are plan, elevation, and bottom views respectively of a terminal plug, FIGURES 1 and 2 being partly in section, and FIGURE 4 is a longitudinal section of the plug as applied to a wire-end;

FIGURES 5 and 6 are transverse sectional views of the plug of FIGURES t1 and 2 at the planes indicated;

FIGURE 7 is an elevation of the face of the bifurcated contact member of FIGURES 13;

FIGURE 8 is a transverse section of the connector of FIGURE 4- showing the contact member applied to the wire-end;

FEGURE 9 represents in perspective the insulating components of a typical terminal block assembly;

FZGURE 19 illustrates in longitudinal cross-section one form of terminal block connector element as contained within a terminal block and with a terminal plug in entering position;

FIGURES 11 and -'12 are transverse cross-sectional views of alternative forms of terminal block connector elements;

FIGURE 13 is a par ial elevational view or a t rminal plug indicating an alternative form of connection; and

FlGURE 14 is longitudinal cross-section of a portion of a terminal block connector showing an alternative method of retaining the connector element.

The terminal plug or pin it of FIGURES 1-4 is conveniently formed of a single fiat piece of spring metal folded and shaped to produce a tubular end section 11, an expanded rectangular centre channel-forming section 32, a square cross-section terminal trough-like contact pin end section 13, and a spring lever member i ending in a bifurcated contact member 15, illustrated also in FIGURE 7. The contact member comprises a pair of spaced opposing jaw members It? and 21?, having narrow work-engaging surfaces including substantially parallel holding portions rounded or otherwise gradually diverging accepting portions forming a work-engaging opening. The ends of the jaws opposite said opening are interconnected by the resilient spring metal of the lever 1 so as to be yieldingly resistant to stresses tending to se; arate them.

A specific example designed for applic tion to plasticor fabric-insulated copper wires or" 2-0 to 24 gage, as used in electronic or communication circuits, is constructed of No. 26 gage (.9159 inch) spring brass sheet. The tubular section 1-1 is .102 inch in outside diameter. The rectangular opening in the central channel 12 is .113 inch wide and 's just sutl'icient length, i.e. in the longitudinal di- $317,329 Fatented Jan. 14, 1964 rection of the plug, to permit easy entry of the contact member The overall length of the plug is about one inch. The open trough 13 is .070 inch inside width, whereas the lever 14 expands gradually from slightly less at the end of the trough to slightly more, i.e. to about .075 inch, in width, near the juncture of the trough 13 and central section 32, so that a tight snap fit is obtained as the lever is pressed into the trough section in the closed position as indicated in FIGURE 4, being then firmly held in closed position by the resiliency of the connector body.

The contact member id of FiGURE 7 is (1.10 inch wide. Each of the two branches or jaw members 1'9, 2% is terminally rounded at a radius of .025 inch and is about .043 inch wide, leaving a central slot .913 inch wide which extends .080 inch from the open end into the contact member. The latter is sharply folded to an angle of with the shank of the lever 14, the length of the contact member being .985 inch as measured from the inner surface of the lever. The tip of the contact member 15 is positioned within the outer portion of the narrow channel provided by the central section 12, and the lever 14 enters the end of the squared trough section, as shown in FIG- URE 2, when the plug is in condition for application to a wire-end.

The lower edge of the central channel-forming section is provided with two slot-like openings -16 each about .017 inch wide and .045 inch long, into which the rounded tips of the two jaw members 19', 2d are designed to enter. The two openings are separated about .015 inch, the remaining segment of the base providing continuous support for the insulated wire and serving to strengthen the structure. In the base and near the end of the section 13 there may be provided a smooth-surfaced opening or depression 22, conveniently about .036 inch in diameter, serving to hold the plug within a terminal block or socket as will subsequently be further described.

FZGURE 4 i lustrates the plug as applied to a wire 17 having a covering of insulation 18. With the wire-end in position as shown, are lever 14 with its attached contact member 15 is pressed into place, e.g. with pliers or side-cutters. The wire-end is supported along its entire length, inc uding the area between the slots 16, against the bottom inner surface of connector. The rounded ends or the jaw members :19, 2% provide a work-engaging opening. As the contact member is forced over the wire, the jaw edges displace the insulating covering 18 and come into sliding contact with the wire 17; at the same time, the wire is slightly deformed and the jaw members are spread apart under strong tension, due to the resiliency of the lever ft-i which at the adjacent end may assun e a slight bow as indicated in FlGU-RE 8. The degree of spreading will depend on the size of the wire to which connection is being made but, within the range of wiresizes for w ich the connector is designed, will be found fully adequate to ensure effective permanent metal-tometal contact. An effective permanent electrical contact is thereby obtained. The snap action provided as the lever 14 enters between the sides of the trough section 13 serves as an indication that the connection has been effectively completed.

The outer edges of the contact member 15 remain at least slightly spaced from the inner edge walls of the channel section 12, as indicated in FIGURE 8, the entire contact pressure between the jaws 19, Ztl and the wire 17 being provided through the resiliency of the metal strip forming the lever 14. In the closed position, the rounded ends of the jaws pass into and through the slots 16 in the base of the channel section. Although the jaws are therefore not laterally restricted, the dimensions of the channel, and more particularly of the slots 16, in the longitudinal direction of the terminal plug are such as to prevent any significant motion of the contact member in such direction. Accordingly it will be seen that the wire 17 is firmly retained within the plug against any longitudinally applied forces. in practice, such plugs may repeatedly be inserted into and removed from connector-blocks entirely by forces applied to the insulated wire, with no loosening and no measurable change in con ductivity between wire and plug.

One form of connection, illustrated in FIGURE 13, employs a coupling lug or link 2-1, attached to the plug 19 at a hole 22 by a screw 23, for fastening to a screw-type binding post 24 or other type of connector by means of a conventional spade or eyelet or other tip. A preferred form of connection makes use of a terminal block assembly of the type exemplified in FIGURE 9, in which are shown two ceramic or plastic multi-cornpartrnent inter-fitting insulating tray members 25, 2s held together by rivets or mounting screws and providing a series of doubly open-ended rectangularly cross-sectioned channels as further indicated in FIGURES l l2.. Some or all of such channels are provided with spring-metal connector elements, of which several types are illustrated.

The element 27 of FIGURE 10 consists of an elongate narrow fiat spring member folded back at each end to form an interconnected pair of leaf springs each provided with a central boss or protrusion 28 designed to fit into a hole or depression 22 in the bottom surface of a terminal plug 10, one of which is to be applied at each end of the element 27. The element is retained within the channel by partial closures 32 at each end thereof.

A diiferent and preferred action is provided by the connector element 2 of FIGURE 11. In this modification all four sides of the square-sectioned end 13 of the terminal plug may be in metal-to-rnetal contact with the spring-metal element 29, the plug being frictionally held in place and in any of the four possible positions by the edges 3% of the element 29 due to the resiliency thereof. The edges provide a high pressure wiping contact during insertion of the plug, thus assuring an efiective electrical connection regardless of incidental corrosion or coating of the plug surface. Similar action is provided by the somewhat diiierent connector element 31 of FEGURE 12. In both instances, the connector element may be held in place within the channelled terminal block by simply inverting the connector element in the partially closed channel of the terminal block of FIGURES 9 and 10, as is indicated in FIGURES l1 and 12. An alternative system is illustrated in FIGURE 14, wherein the channels formed between the trays 25 and 2e are completely open at the ends but are provided with a raised central wedge or partial cross-member 3E5 fitting within a corresponding central open transverse slot in the base of the connector element 29'. r

The invention has for convenience been described primarily in terms of individual terminal wire-connectors suitable for attaching to a single wire-end. Multiplewire connectors employing identical principles are also to be included. They may be made as a continuation of the connector of FIGURES 1-4, for example by interconnection of identical spring-metal blanks along mutual free edges of corresponding end sections 13. Another form employs two or more tubular wire-receiving members placed in side-by-side relationship, and a multipleopening contact member fitting within a transverse channel crossing the several wlre-receiving members. In a further form, the connector may initially be open at an upper sidefor insertion of a wire loop, the two sides of the loop then being separately contacted and held in position by appropriate bifurcate contact members fitting within transverse channel openings. Where two or more Wire-ends are thus interconnected, each serves as a connecting means for the other, no additional connecting pin or lug then being required. in all instances there is provided a wire-connector having an open-ended transversely slotted body section and a slotted contact member fitting into the slotted bod and roviding ermanent 1 l yieldin ly resilient contact for the wire while preventing lon itudinal movement of the wire w thin the connector.

What is claimed is as follows:

1. A terminal pin type wire-connector comprising an elongate metallic tubular member having an entrant section, a short central open-top contact-retaining section, a trough-like connecting-pin section, and a spring-lever section terminating in a bifurcate contact member complising a pair of terminally resiliently interconnected 0pposing jaw members having narrow wire-engaging surfaces including substantially parallel holding portions and gradually diverging accepting portions forming a wireengaging opening; said contact member fitting within said open-top central section with sufficient lateral clearance to avoid lateral constriction of said jaws as they are resiliently separated on being forced over a wire placed therebetween for connection thereto and with just sufficient longitudinal clearance to permit easy entry of said contact member; and said spring-lever section being of a width just suihcient for snugly fitting between the open sides of said trough-like section in retentive snap fit relationship when said contact member is within said central section.

2. The wire-connector of claim 1 in which the bottom side of said central section is open at both sides of a cenral wire-supporting area to receive the ends of said jaw members without lateral constriction thereof.

3. An insulated wire having attached at an end thereof a terminal pin-type wire-connector suitable for pin-andsocket type connections, said connector having a conductive metallic square cross-section terminal portion for insertion into an electrically contacting socket, a circular cross-section wire-receiving initial portion loosely fitting around said insulated wire, an intermediate short channel-forming portion, and a bifurcate contact member retained within said channel in permanent resilient electrical contact with said wire and restrained from movement longitudinally of said connector, said contact member comprising a pair of spaced opposing jaw members having narrow Work-engaging surfaces including substantially parallel holding portions and gradually diverging accepting portions forming a wire-engaging opening, said jaw members being interconnected at the ends opposite said opening by resilient holding means yieldingly resistant to stresses tending to separate said surfaces.

4. A terminal block assembly for pin-and-socket interconnection of electrical components as defined in claim 3, comprising at least two interfitting insulating tray members providing doubly open-ended channels each having at least one partial cross-member and each containing a double-ended spring contact member retained therein by said cross-member, and wherein said contact member comprises a thin rectangular plate of spring metal folded into elongate square tube form with at east one longitudinal edge directed inwardly of the tube to provide resilient wiping contact with an inserted pintype wire-connector.

5. A onepiece metallic terminal pin type wire-connector including, disposed along a central axis, (1) a wire-accepting first end section in extended open-ended tubular form tor insertion of a wire-end; (2) a short central section of increased width, open at one side to provide a U-shaped cross-section, the base of the U being open at least at both extremities; (3) a contact-forming second end section in extended open trough-like form having a U-shaped cross-section; (4) an elongate fiat strip element extending as a continuation of the base of said trough-like second end section and disposed across the open end and extending above the open side thereof, said strip bein of a width just suihcient to provide a snap l t between the edge extremities of said trough-like section to form a closed rectangular cross-sectioned terminal pin; and (5) a bifurcate contact plate extending as a terminal continuation of said fiat strip and in position for sliding into said central section through the open side thereof as said strip is snapped into said second end section; said contact plate having a pair of terminally resiliently interconnected opposing jaw members having narrow Wire-engaging surfaces including substantially parallel holding portions and gradually diverging accepting portions forming a Wire-engaging opening; said contact plate fitting Within said central section with sufficient lateral clearance to avoid lateral constriction of said jaws as they are resiliently separated on being forced over a Wire placed therebetween for connection thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,764,227 Robinson June 17, 1930 Carson Oct. 10, Galvao Apr. 22, Felts et a1. Mar. 3, Burtt et a1 Sept. 14, French Oct. 9, Hewes et al Feb. 9, Levin et al Dec. 5,

FOREIGN PATENTS Great Britain Dec. 7, Great Britain Ian. 11, Switzerland Dec. 1, 

1. A TERMINAL PIN TYPE WIRE-CONNECTOR COMPRISING AN ELONGATE METALLIC TUBULAR MEMBER HAVING AN ENTRANT SECTION, A SHORT CENTRAL OPEN-TOP CONTACT-RETAINING SECTION, A TROUGH-LIKE CONNECTING-PIN SECTION, AND A SPRING-LEVER SECTION TERMINATING IN A BIFURCATE CONTACT MEMBER COMPRISING A PAIR OF TERMINALLY RESILIENTLY INTERCONNECTED OPPOSING JAW MEMBERS HAVING NARROW WIRE-ENGAGING SURFACES INCLUDING SUBSTANTIALLY PARALLEL HOLDING PORTIONS AND GRADUALLY DIVERGING ACCEPTING PORTIONS FORMING A WIREENGAGING OPENING; SAID CONTACT MEMBER FITTING WITHIN SAID OPEN-TOP CENTRAL SECTION WITH SUFFICIENT LATERAL CLEARANCE TO AVOID LATERAL CONSTRICTION OF SAID JAWS AS THEY ARE RESILIENTLY SEPARATED ON BEING FORCED OVER A WIRE PLACED THEREBETWEEN FOR CONNECTION THERETO AND WITH JUST SUFFICIENT LONGITUDINAL CLEARANCE TO PERMIT EASY ENTRY OF SAID CONTACT MEMBER; AND SAID SPRING-LEVER SECTION BEING OF A WIDTH JUST SUFFICIENT FOR SNUGLY FITTING BETWEEN THE OPEN SIDES OF SAID TROUGH-LIKE SECTION IN RETENTIVE SNAP FIT RELATIONSHIP WHEN SAID CONTACT MEMBER IS WITHIN SAID CENTRAL SECTION. 